View full sizeAnja Niedringhaus, The Associated PressA Libyan rebel fires a gun in the city of Ajdabiya, south of Benghazi, in eastern Libya, on Saturday. The graffiti on the car reads 'Army of Libya.'

Ajdabiya's initial fall to Gadhafi may have ultimately been what saved the rebels from imminent defeat, propelling the U.S. and its allies to swiftly pull together the air campaign now crippling Gadhafi's military. Its recapture gives President Barack Obama a tangible victory just as he faces criticism for bringing the United States into yet another war.

In Ajdabiya, drivers honked in celebration and flew the tricolor rebel flag. Others in the city fired guns into the air and danced on burned-out tanks that littered the road.

Their hold on the east secure again, the rebels promised to resume their march westward that had been reversed by Gadhafi's overwhelming firepower. Rebel fighters already had pushed forward to the outskirts of the oil port of Brega and were hoping to retake the city on Sunday, opposition spokeswoman Iman Bughaigis said, citing rebel military commanders.

"Without the planes we couldn't have done this. Gadhafi's weapons are at a different level than ours," said Ahmed Faraj, 38, a rebel fighter from Ajdabiya. "With the help of the planes we are going to push onward to Tripoli, God willing."

The Gadhafi regime acknowledged the airstrikes had forced its troops to retreat and accused international forces of choosing sides.

"This is the objective of the coalition now, it is not to protect civilians because now they are directly fighting against the armed forces," Khaled Kaim, the deputy foreign minister, said in Tripoli. "They are trying to push the country to the brink of a civil war."

Ajdabiya's sudden capture by Gadhafi's troops on March 15 -- and their move toward the rebel capital of Benghazi -- gave impetus to the U.N. resolution authorizing international action in Libya, and its return to rebel hands on Saturday came after a week of airstrikes and missiles against the Libyan leader's military.

Airstrikes Friday on the city's eastern and western gates forced Gadhafi's troops into hasty retreat. Inside a building that had served as their makeshift barracks and storage, hastily discarded uniforms were piled in the bathroom and books on Islamic and Greek history and fake pink flowers were scattered on the floor.

Saif Sadawi, a 20-year-old rebel fighter with a rocket-propelled grenade launcher in his hands, said the city's eastern gate fell late Friday and the western gate fell at dawn Saturday after airstrikes on both locations.

"All of Ajdabiya is free," he said.

Rebels swept into the city and hauled away a captured rocket launcher and a dozen boxes of anti-aircraft ammunition, adding to their limited firepower. Later in the day, other rebels drove around and around a traffic circle, jubilantly firing an assortment of weapons in the air -- anti-aircraft weapons, AK-47s, RPGs.

Outside the city, Muftah el-Zewi was driving away, his back seat loaded with plastic bags filled with blankets and clothes that he picked up after going to his home in Ajdabiya for the first time in days.

"We went and checked it out, drove around the neighborhood and it looked OK. Hopefully we'll come back to stay tomorrow," he said.

The turnaround is a boost for Obama, who has faced complaints from lawmakers from both parties that he has not sought their input about the U.S. role in the conflict or explained with enough clarity about the American goals and exit strategy. Obama was expected to give a speech to the nation Monday.

"We're succeeding in our mission," Obama said in a radio and Internet address. "So make no mistake, because we acted quickly, a humanitarian catastrophe has been avoided and the lives of countless civilians -- innocent men, women and children -- have been saved."

The U.N. Security Council authorized the operation to protect Libyan civilians after Gadhafi launched attacks against anti-government protesters who demanded that he step down after 42 years in power. The airstrikes have crippled Gadhafi's forces, but rebel advances have also foundered, and the two sides have been at stalemate in key cities.

Ajdabiya, the gateway to the opposition's eastern stronghold, and the western city of Misrata have suffered under sieges of more than a week because the rebels lack the heavy weapons to push out Gadhafi's troops. Residents lack electricity, phone lines and water.

A doctor in Misrata said airstrikes there on Saturday put an end to two days of shelling and sniper fire from Gadhafi's forces. The city was quiet Saturday afternoon, said the doctor, speaking on condition of anonymity because he feared for his safety if the city should fall. For now, he said, rebels control the city center, just as they have throughout in Ajdabiya.

A resident of Zwara, a former rebel stronghold in the west, said the regime has the town firmly in its grip again. He said pro-Gadhafi forces are dragging away people there and in the town of Zawiya who participated in protests that began Feb. 15.

"They have lists of demonstrators and videos and so on and they are seeking them out. We are all staying home and waiting for this to be over," said the resident, who did not want to be named because he feared for his safety if discovered. He said a friend who helped coordinate checkpoints when the opposition held the city was taken away Friday.

"They came with four or five cars with four people in each one, all of them armed to the teeth with Kalashnikovs. They surrounded the house and took him out," he said, adding that the whole thing was seen by a common friend.

He said neighbors now fear each other.

"During the demonstrations, many people contributed to the community, doing anything they could. This shows that the regime has collaborators to give them names. It's a Big Brother type of show, so they can come in and take whomever they want."

The government's grip has even tightened in Tripoli, its seat of power, where almost nightly airstrikes have hammered military bases, missile storage and even Gadhafi's residential compound.

Rahma, a Libyan-American in the capital, said only about one in 20 stores was open and food supplies were dwindling by the day.

"My own family, we've just been staying inside, but we had a friend who went to Friday prayers and they could see people ready to shoot them hiding behind the bushes," she said. She did not want her surname used, for fear of retaliation. "This is at every mosque, so if they start to protest, they'll get shot right away."

Ben Hubbard and Ryan Lucas of The Associated Press wrote this report. Hubbard contributed from Cairo. Hadeel al-Shalchi contributed from Tripoli, Libya.